A kinematic model for the East African Rift

Stamps, D. S.; Calais, E.; Saria, E.; Hartnady, Chris; Nocquet, Jean‐Mathieu; Ebinger, C. J.; Fernandes, Rui

doi:10.1029/2007gl032781

Cited by 273 publications

(290 citation statements)

References 25 publications

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“…1) (e.g., Fernandes et al, 2004;Jestin et al, 1994;Stamps et al, 2008). Similar models suggest ∼ 15 mm/yr of ∼ N35°E directed opening across the western Gulf of Aden rift (e.g., Jestin et al, 1994).…”

Section: Current Plate Motionsmentioning

confidence: 65%

The development of extension and magmatism in the Red Sea rift of Afar

et al. 2013

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Despite the importance of continental breakup in plate tectonics, precisely how extensional processes such as brittle faulting, ductile plate stretching, and magma intrusion evolve in space and time during the development of new ocean basins remains poorly understood. The rifting of Arabia from Africa in the Afar depression is an ideal natural laboratory to address this problem since the region exposes subaerially the tectonically active transition from continental rifting to incipient seafloor spreading. We review recent constraints on along-axis variations in rift morphology, crustal and mantle structure, the distribution and style of ongoing faulting, subsurface magmatism and surface volcanism in the Red Sea rift of Afar to understand processes ultimately responsible for the formation of magmatic rifted continental margins. Our synthesis shows that there is a fundamental change in rift morphology from central Afar northward into the Danakil depression, spatially coincident with marked thinning of the crust, an increase in the volume of young basalt flows, and subsidence of the land towards and below sea-level. The variations can be attributed to a northward increase in proportion of extension by ductile plate stretching at the expense of magma intrusion. This is likely in response to a longer history of localised heating and weakening in a narrower rift. Thus, although magma intrusion accommodates strain for a protracted period during rift development, the final stages of breakup are dominated by a phase of plate stretching with a shift from intrusive to extrusive magmatism. This late-stage pulse of decompression melting due to plate thinning may be responsible for the formation of seaward dipping reflector sequences of basalts and sediments, which are ubiquitous at magmatic rifted margins worldwide.

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Section: Current Plate Motionsmentioning

confidence: 65%

The development of extension and magmatism in the Red Sea rift of Afar

et al. 2013

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“…Lower-right inset shows a schematic profile along AA′. The rift extension direction in this area is about N110 E [Stamps et al, 2008]. The Goma-Gisenyi urban area is circled in white.…”

Section: Geologic Settingmentioning

confidence: 99%

“…in geophysical, geochemical and geomorphological data [Chorowicz, 2005]. Spreading rates decrease from 6.5 mm/ year in the north of the rift to 1.5 mm/year in the south of the rift [Stamps et al, 2008]. In the Virunga Volcanic Province (VVP), where the rift trend is NNE, with localized NE trends, the spreading rate has an intermediate value of 2.8 cm.…”

Section: Geologic Settingmentioning

confidence: 99%

“…[77] Both dikes are subvertical and more or less perpendicular to the rift extension direction (Figure 1) [Stamps et al, 2008], the shallowest dike deviating more from the extension direction than the deeper dike. Northwest of the Nyiragongo edifice, the shallower dike follows the N20 W weakness direction [Meyer, 1953] linking Nyamulagira and Nyiragongo, while further south the dike follows the northsouth direction taken during the course of the 1977 eruption.…”

Section: Influence Of the Rift Extension On The Dike Directionsmentioning

confidence: 99%

“…The Goma-Gisenyi urban area is circled in white. The rift extension in the Kivu area is derived from Stamps et al [2008]. SKVP and VVP stand for South Kivu Volcanic and Virunga Volcanic Province, respectively.…”

Section: Geologic Settingmentioning

confidence: 99%

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Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Wauthier¹,

Cayol²,

Kervyn³

et al. 2012

J. Geophys. Res.

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along a 20 km-long fracture network extending from the volcano to the city of Goma. The event was captured by InSAR data from the ERS-2 and RADARSAT-1 satellites. A combination of 3D numerical modeling and inversions is used to analyze these displacements. Using Akaike Information Criteria, we determine that a model with two subvertical dikes is the most likely explanation for the 2002 InSAR deformation signal. A first, shallow dike, 2 km high, is associated with the eruptive fissure, and a second, deeper dike, 6 km high and 40 km long, lies about 3 km below the city of Goma. As the deep dike extends laterally for 20 km beneath the gas-rich Lake Kivu, the interaction of magma and dissolved gas should be considered as a significant hazard for future eruptions. A likely scenario for the eruption is that the magma supply to a deep reservoir started ten months before the eruption, as indicated by LP events and tremor. Stress analysis indicates that the deep dike could have triggered the injection of magma from the lake and shallow reservoir into the eruptive dike. The deep dike induced the opening of the southern part of this shallow dike, to which it transmitted magma though a narrow dike. This model is consistent with the geochemical analysis, the lava rheology and the pre-and post-eruptive seismicity. We infer low overpressures (1-10 MPa) for the dikes. These values are consistent with lithostatic crustal stresses close to the dikes and low magma pressure. As a consequence, the dike direction is probably not controlled by stresses but rather by a reduced tensile strength, inherited from previous rift intrusions. The lithostatic stresses indicate that magmatic activity is intense enough to relax tensional stresses associated with the rift extension.

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Deep crustal earthquakes in North Tanzania, East Africa: Interplay between tectonic and magmatic processes in an incipient rift

Albaric

Déverchère

Perrot

et al. 2014

Geochem Geophys Geosyst

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[1] In this study, we explore the origin of lower crustal seismicity and the factors controlling rift propagation using seismological data recorded within the youngest part of the East African Rift System, the North Tanzanian Divergence (NTD). Most earthquakes below Lake Manyara occur at depth ranging between 20 and 40 km and have a swarm-like distribution. Focal mechanisms of 26 events indicate a combination of strikeslip and normal faulting involving Archaean basement structures and forming a relay zone. The derived local stress regime is transtensive and the minimum principal stress is oriented N110 E. Crustal seismic tomography reveals low-velocity anomalies below the rifted basins in the NTD, interpreted as localized thermomechanical perturbations promoting fluid release and subsequent seismicity in the lower crust. SKS splitting analysis in the NTD indicates seismic anisotropy beneath 17 stations most likely due to aligned magma lenses and/or dikes beneath the rift and to the lithospheric fabrics. Our results favor a strain pattern intermediate between purely mechanical and purely magmatic. We suggest that melt products arising from a large asthenospheric thermal anomaly enhance lithospheric weakening and facilitate faulting and creeping on critically oriented inherited structures of the Precambrian lower crust. Although the crust is unlikely weakened at a point comparable to other parts of the East African Rift System, this deep-seated thermomechanical process is efficient enough to allow slow rift propagation within the eastern Tanzanian cratonic edge.

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A kinematic model for the East African Rift

Cited by 273 publications

References 25 publications

The development of extension and magmatism in the Red Sea rift of Afar

The development of extension and magmatism in the Red Sea rift of Afar

Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Deep crustal earthquakes in North Tanzania, East Africa: Interplay between tectonic and magmatic processes in an incipient rift

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